Fig. 4

Comparison of a synthetic PK-PTA-AADH pathway (left, blue) and native metabolism of xylulose-5-phosphate (right) via pentose phosphate pathway and glycolysis. The synthetic pathway is more carbon-conserving in ethanol production, compared to native metabolism, due to its absence of carbon losing enzymatic reactions, such as pyruvate decarboxylase. The dotted arrow indicates promiscuous acetyl phosphate phosphatase activities of S. cerevisiae